1. Field of the Invention
This invention is related to coupling mechanisms in general and more particularly to coupling mechanisms intended for use with connectors, most particularly with fiber optic connectors.
2. Description of Related Art
Connectors of the type to which the present invention pertains are typically used to connect links of a cable in series to form a composite cable assembly which is longer than that which could be conveniently handled if it were made of a single continuous cable. In these and other applications of connectors, it is of paramount importance that their interconnection be easily effected and yet secure. These requirements have not always been met by currently available connectors due to the shortcoming of their coupling mechanisms. One widely-used coupling mechanism for connectors is of the screw and nut type found most frequently on military connectors, both electrical and fiber optic. The coupling mechanism comprises a coupling ring having an internal thread and the mating connector's shell having an external thread. The only locking mechanisms provided are holes through which a locking wire may be threaded. The use of a locking wire has several disadvantages. It may not always be attached and, once the connector is unmated, it may not be replaced. Moreover, the locking wire is inconvenient to apply. It requires a suitable tool to cut and remove the wire, after which the coupling ring must be turned through several rotations in order to unmate the connector. Similarly, mating of the connector requires several rotations and tools are needed to apply the locking wire to complete the mating process.
A second type of widely-used coupling mechanism is that found on the bayonet coupling type of connector. It consists of a coupling ring having an internal cam track in a configuration that provides an inclined plane and a locking contour. The coupling ring mates with bayonet pins attached to the shell of the mating connector. During mating the bayonet pins ride in the cam track. As the coupling ring is rotated, the bayonet pins guide the connector to its mated condition. In the final stages of the mating sequence, a wave spring washer is compressed and the bayonet pins drop into a locking recess in the cam track of the coupling ring.
The bayonet coupling type connector is easier to unmate and to remate than is the screw and nut type. Typically, to disengage the connector from its counterpart the coupling ring simply needs to be rotated approximately 100.degree. counterclockwise rather than through several turns. Engagement is also relatively quick, requiring rotation of only about 100.degree. clockwise to engage and making sure that full engagement occurs by listening for an audible click as the bayonet pins drop into their locking position. The need for a locking wire, thus, is obviated. Notwithstanding these advantages of the bayonet coupling type connector, it has several serious disadvantages. Among them is the wear caused by the high pressure between the bayonet pins and the cam track in which they ride. Moreover, since the connectors are held in their mated condition by the force supplied by the wave washer, they can be inadvertently disconnected, since cable tension can overcome the force generated by the wave washer. Finally, the rotary torque that has to be exerted upon the coupling ring to overcome the locking position in the course of disengaging the connectors can be quite high.
Accordingly, it is a general object of the present invention to provide an improved coupling mechanism, primarily for connectors, which is self locking and which is secure from disengagement due to vibration and shock.
It is a related object of the present invention to provide a quickly attachable and detachable connector capable of mating with an identical counterpart, and which is held in secure contact therewith.
Another object of the present invention is to provide an optical connector which will securely seal its contacts while mating them with precise force, and which is capable of engaging its identical counterpart.
Other objects and advantages of the invention will become apparent as this description proceeds.
In fiber optic connectors it is very important that the contact elements in a pair of mating connectors be accurately aligned with respect to each other along their mutual axes, or, in other words, that they be precisely coaxial. Otherwise, their respective optic fibers will be imperfectly aligned so that part of the light emanating from the tip of one fiber will fail to enter the tip of the other fiber. A common expedient for insuring precise alignment of fiber optic contacts is to use an alignment tube into which the tips of both fiber optic contact assemblies enter. It is apparent that an entire alignment tube for a particular contact pair cannot be located on both connectors; that it has to be carried either on one connector or the other. Consequently, a conventional alignment tube cannot be used on a single contact hermaphroditic connector.
Accordingly, it is another principal object of the present invention to provide alignment tube segments for a connector, and particularly for a fiber optic connector, which are axially interfitting and mutually complementary so that when they are interfitted they will constitute an alignment tube having a single longitudinal axis.
It is a related object of the present invention to provide a pair of axially-interfitting, mutually-complementary alignment tube segments which when interfitted constitute an alignment tube having a single longitudinal axis for precisely aligning a pair of cylindrical tips, which may be bushings, carried by a pair of contact assemblies. Moreover, it is an additional object of the invention so to configure the interfitting alignment tube segments that in the process of interfitting they conform to the contours of the bushings held within them, thereby forcing the bushings into precise axial alignment.